Extrusion die for metallic material

ABSTRACT

In some preferred, embodiments, an extrusion die for a metallic material capable of obtaining a high quality extruded article can be provide while securing sufficient strength and durability. The die is provided with a male die case  20  having a pressure receiving portion  21 , a female die case  25 , a male die  30  provided in the male die case  20 , and a female die  40  provided in the female die case  25 . The pressure receiving portion  21  is formed into a convex configuration protruded rearward, and a porthole for introducing a metallic material is formed in the external periphery of the pressure receiving portion. A press-fitting connecting portion  21   a  is formed at the front side of the male die case  20  and a press-fitting dented portion  25   a  is formed at the rear side of the female die case  25 . The press-fitting connecting portion  21   a  is fitted in the press-fitting dented portion  25   a  to thereby connect both the die cases  20  and  25  with the male die case  20  restrained from its periphery thereof by the female die case  25.

This application claims priority to Japanese Patent Application No. 2006-187944 filed on Jul. 7, 2006, Japanese Patent Application No. 2007-56656 filed on Mar. 7, 2007, and U.S. Provisional Application Ser. No. 60/887,054 filed on Jan. 29, 2007, the entire disclosures of which are incorporated herein by reference in their entireties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an application filed under 35 U.S.C. §111(a) claiming the benefit pursuant to 35 U.S.C. §119(e)(1) of the filing date of Ser. No. 60/887,054 filed on Jan. 29, 2007, pursuant to 35 U.S.C. §111(b).

TECHNICAL FIELD

The present invention relates to an extrusion die for a metallic material used for extruding a metallic material and its related art.

BACKGROUND ART

As an extrusion die used for manufacturing a metal hollow extruded product, such as, e.g., an aluminum heat exchanging tube for use in a heat exchanger for car air-conditioners, there are a porthole die as shown in FIG. 18A, a spider die as shown in FIG. 18B, and a bridge die as shown in FIG. 18C.

In these extrusion dies, a male die 1 and a female die 2 are combined with the mandrel 1 a of the male die 1 placed in the corresponding die hole 2 a of the female die 2 to define a circular extrusion hole by and between the mandrel 1 a and the die hole 2 a. A metal billet (metallic material) pressed against the billet pressure receiving surface (metallic material pressure receiving surface 1 b) of the male die 1 is introduced in both the dies 1 and 2 via material introduction holes 1 c and then passed through the extrusion hole while being plastically deformed, so that an extruded member having a cross-section corresponding to the cross-sectional configuration of the extrusion hole is formed.

In such an extrusion die, since large stress due to pressing of the metal billet is applied to the billet pressure receiving surface 1 b of the male die 1, the stress may cause generation of cracks in the periphery of the pressure receiving portion of the die, which may sometimes make it difficult to attain sufficiently long die life.

Under the circumstances, an extrusion die for a metallic material as disclosed by the below-listed Patent Documents 1 and 2 has been conventionally proposed. In the die, the billet pressure receiving surface of the male die is formed into a convex shape protruded in a direction opposite to the billet extruding direction (i.e., protruded rearward) so that the pressing force of the metallic billet to be applied to the billet pressure receiving surface can be received by a bridge portion of the male die.

Patent Document 1: Japanese Unexamined Laid-open Utility Model Publication No. S53-102938 (see claims, FIGS. 3-5)

Patent Document 2: Japanese Examined Laid-open Patent Publication No. H06-81644 (see claims, drawings)

In the conventional extrusion die disclosed in the aforementioned Patent Documents 1 and 2, since the billet pressure receiving surface is formed into a convex configuration, the bridge portion is still insufficient in strength although the strength of the male die, such as the resistance to pressure against a metal billet, can be improved to some extent. Therefore, in order to secure sufficient strength of the bridge portion, the size of the male die such as the thickness of the bridge portion has to be increased, which results in not only an increased size and weight but also an increased cost.

Especially in the case of extruding an extruded article having a complicated configuration using an extrusion die, it is necessary to stably and smoothly introduce the metal material into the extrusion hole from the material introducing portion of the male die. In the aforementioned conventional extrusion die, however, the metallic material which flows from the material introducing portion of the male die into the space between the male die and the female die is disturbed by the bridge portion of the male die. This prevents smooth introduction of the metallic material, causing deteriorated dimensional accuracy of the extruded article, which in turn makes it difficult to attain high quality.

The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. Indeed, certain features of the invention may be capable of overcoming certain disadvantages, while still retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.

Other objects and advantages of the present invention will be apparent from the following preferred embodiments.

DISCLOSURE OF INVENTION

The preferred embodiments of the present invention have been developed in view of the above-mentioned and/or other problems in the related art. The preferred embodiments of the present invention can significantly improve upon existing methods and/or apparatuses.

The present invention was made to solve the aforementioned problems of the conventional technique, and aims to provide an extrusion die for a metallic material capable of obtaining a high quality extruded article while reducing the cost and size of the die and securing sufficient strength and durability of the die.

The present invention also aims to provide related technologies capable of attaining the aforementioned objects, such as, e.g., a production method of an extruded article, a production method of an extruded tubular member, a production method of a multi-bored hollow member, a die case for an extrusion die, an extrusion method of a metallic material, and an extruder for a metallic material.

The present invention provides the following means to attain the aforementioned objects.

[1] An extrusion die for a metallic material, comprising:

a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material;

a female die case disposed at a front side of the male die case:

a male die provided in the male die case; and

a female die provided in the female die case to form an extrusion hole by and between the female die and the male die, wherein the metallic material pressure receiving surface of the pressure receiving portion is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is formed in an external periphery of the pressure receiving portion,

wherein a press-fitting connecting portion is formed at a front side external periphery of the male die case, and a press-fitting dented portion is formed at a rear side external periphery of the female die case, and

wherein the press-fitting connecting portion is press-fitted in the press-fitting dented portion, whereby both the die cases are connected with each other with the male die case restrained from periphery thereof by the female die case.

[2] The extrusion die for a metallic material as recited in the aforementioned Item 1, wherein an axis of the porthole is disposed so as to incline with respect to an axis of the male die case so that the axis of the porthole approaches the axis of the male die case toward a downstream side.

[3] The extrusion die for a metallic material as recited in the aforementioned Item 1 or 2, wherein a radius direction compression rate (press-fitting margin) of the press-fitting connecting portion with respect to the press-fitting dented portion is set to 1 to 8%.

[4] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 3, wherein the male die case and the male die are formed separately, and the male die is held by the male die case.

[5] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 3, wherein the male die is integrally formed to the male die case.

[6] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 5, wherein the female die is integrally formed to the female die case.

[7] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 6, wherein a flow control plate for controlling a metallic material flow is integrally formed to the male die case.

[8] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 7, wherein the pressure receiving portion is formed into a semi-spherical configuration.

[9] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 7, wherein the metallic material pressure receiving surface is constituted by a convex spherical surface of a ⅙ to 4/6 sphere.

[10] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 7, wherein the pressure receiving portion is formed into a polyhedral configuration in which a plurality of side surfaces are disposed on the pressure receiving surface.

[11] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 7, wherein the pressure receiving portion is formed to have an elliptical or oval configuration as seen from an axial direction of the male die case.

[12] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 7, wherein a protrusion dimension of the pressure receiving portion along an axial direction of the male die case is set to be longer than a radius dimension of the pressure receiving portion along a direction perpendicular to the axial direction, and wherein the pressure receiving portion is formed to have a semi-elliptical or semi-oval configuration as seen from a direction perpendicular to the axial direction.

[13] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 12, wherein the male die case has a plurality of the portholes arranged at equal intervals in a peripheral direction around an axis of the male die case.

[14] The extrusion die for a metallic material as recited in the aforementioned Item 2, wherein an inclination angle of the axis of the porthole is set to 3 to 350 with respect to the axis of the male die case.

[15] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 14, wherein the metallic material is aluminum or aluminum alloy.

[16] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 15, wherein a circular extrusion hole is formed by and between the male die and the female die so that the metallic material is extruded through the extrusion hole to form a tubular member circular in cross-section.

[17] The extrusion die for a metallic material as recited in any one of the aforementioned Items 1 to 15,

wherein an extrusion hole having a flat circular cross-sectional configuration with a height (thickness) smaller than a width is formed by the male die and the female die,

wherein a portion of the male die corresponding to the extrusion hole is formed into a comb-line configuration having a plurality of passage forming protrusions arranged in a width direction, and

wherein the metallic material passes through the extrusion hole to form a multi-bored hollow extruded member having a plurality of passages arranged in a width direction.

[18] An extruded article production method for producing an extruded article by using the extrusion die as recited in any one of the aforementioned Items 1 to 15.

[19] An extruded tubular member production method for producing an extruded tubular member by using the extrusion die as recited in the aforementioned Item 16.

[20] A multi-bored hollow member production method for producing a multi-bored hollow member by using the extrusion die as recited in the aforementioned Item 17.

[21] A die case for en extrusion die, comprising:

a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material, and a male die being provided in the male die case; and

a female die case disposed at a front side of the male die case, a female die being provided in the female die case,

wherein the metallic material pressure receiving surface of the pressure receiving portion is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is formed in an external periphery of the pressure receiving portion,

wherein a press-fitting connecting portion is formed at a front side external periphery of the male die case, and a press-fitting dented portion is formed at a rear side external periphery of the female die case, and

wherein the press-fitting connecting portion is press-fitted in the press-fitting dented portion, whereby both the die cases are connected with each other with the male die case restrained from periphery thereof by the female die case.

[22] The die case for an extrusion die as recited in the aforementioned Item 21, wherein the metallic material pressure receiving surface is constituted by a convex spherical surface of a ⅙ to 4/6 sphere.

[23] A metallic material extrusion method, comprising the steps of:

preparing a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material, a female die case disposed at a front side of the male die case, a male die provided in the male die case, and a female die provided in the female die case to form an extrusion hole by and between the male die and the female die;

forming a porthole for introducing a metallic material in an external periphery of the pressure receiving portion having a convex configuration constituting the metallic material pressure receiving surface protruded rearward;

forming a press-fitting connecting portion at a front side external periphery of the male die case and forming a press-fitting dented portion at a rear side external periphery of the female die case;

connecting both the die cases with the male die case restrained from its periphery thereof by the female die case by press-fitting the press-fitting connecting portion into the press-fitting dented portion; and

introducing the metallic material pressed against the metallic material pressure receiving surface in both the die cases via the porthole with both the die cases connected to thereby pass through the extrusion hole.

[24] A metallic material extruder comprising a container and an extrusion die set in the container, the extruder being configured to supply a metallic material in the container to the extrusion die,

wherein the extrusion die comprises:

a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material;

a female die case disposed at a front side of the male die case;

a male die provided in the male die case; and

a female die provided in the female die case to form an extrusion hole by and between the male die and the female die,

wherein the metallic material pressure receiving surface of the pressure receiving portion is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is formed in an external periphery of the pressure receiving portion,

wherein a press-fitting connecting portion is formed at a front side external periphery of the male die case and a press-fitting dented portion is formed at a rear side external periphery of the female die case,

wherein both the die cases are connected with each other with the male die case restrained from its periphery thereof by the female die case by press-fitting the press-fitting connecting portion into the press-fitting dented portion, and

wherein the metallic material pressed against the metallic material pressure receiving surface is introduced in both the die cases via the porthole to thereby pass through the extrusion hole.

EFFECTS OF THE INVENTION

According to the extrusion die for a metallic material as recited in the aforementioned Item [1], since the male die case having the metallic material pressure receiving surface is connected to the female die case with the male die case restrained from its periphery thereof by the female die case, the strength of the male die case can be increased, which in turn can increase the strength of the entire die and the durability. Since a predetermined strength can be secured, it is not required to increase the size, such as, e.g., the thickness, beyond necessity, resulting in reduced size and weight, which in turn can reduce the production cost.

Furthermore, according to this extrusion die, since the metallic material pressure receiving surface is formed into a convex configuration, when the metallic material is pressed against the pressure receiving surface, the pressing force of the metallic material can be received by the convex surface in a dispersed manner, which in turn can reduce the pressing force in the direction of the normal line at each portion of the pressure receiving surface. As a result, the strength against the pressing force of the metallic material can be improved, resulting in sufficient durability. That is, when the metallic material is pressed against the pressure receiving surface formed into a convex configuration, since the compression force toward the axis of the pressure receiving portion is applied to each portion of the pressure receiving surface, the shearing force to be generated in the die case at the time of extrusion can be reduced. As a result, as to the portion exposed to the hollow portion of the die case, which is a portion where a larger shearing force is applied in this die case, the shearing force to be generated at the portion can be reduced, which can improve the strength of the die against the pressing force of the metallic material.

According to the extrusion die for a metallic material as recited in the aforementioned Item [2], since an axis of the porthole is disposed so as to incline with respect to an axis of the male die case so that the axis of the porthole approaches the axis of the male die case toward a downstream side, the metallic material passing through the porthole is introduced toward the axis of the male die case, i.e., toward the extrusion hole, which enables a steady extrusion. As a result, a high quality extruded article can be obtained.

According to the extrusion die for a metallic material as recited in the aforementioned Item [3], the male die case can be held by the female die case by an appropriate force, which can further improve the die strength.

According to the extrusion die for a metallic material as recited in the aforementioned Item [4], since the male die case and the female die case are separated, the structures of these die cases can be simplified.

According to the extrusion die for a metallic material as recited in the aforementioned Item [5] to [7], the male die case is integrally formed to the female die case, the number of parts can be reduced.

According to the extrusion die for a metallic material as recited in the aforementioned Item [8] to [12], since the metallic material pressure receiving surface is formed into a predetermined convex configuration, when the metallic material is pressed against the pressure receiving surface, the pressing force of the metallic material can be received in a dispersed manner, which in turn can reduce the pressing force in the direction of the normal line at each portion of the pressure receiving surface. This improves the strength against the pressing force of the metallic material, which in turn can assuredly obtain sufficient durability.

Especially, according to the extrusion die for a metallic material as recited in the aforementioned Item [9], the pressing force of the metallic material against the pressure receiving surface can be more assuredly dispersed in a balanced manner, resulting in more assuredly improved strength against the metallic material pressing force. That is, when the metallic material is pressed against the pressure receiving surface constituted by a specific convex sphere, the compression force toward the center of the pressure receiving surface is more assuredly applied to each portion of the pressure receiving portion, which can more assuredly reduce the shearing force to be generated in the die case at the time of extrusion. As a result, in this die case too, as to the portion exposed to the hollow portion of the die case, which is a portion where the larger shearing force is applied in this die case, the shearing force to be generated at the portion can be more assuredly reduced, which can more assuredly improve the strength of the die against the pressing force of the metallic material.

According to the extrusion die for a metallic material as recited in the aforementioned Item [13], since a plurality of the portholes are arranged in a peripheral direction, the metallic material can be evenly introduced in both the die cases from the peripheral direction, resulting in smooth supply to the extrusion hole, which enables more steady extrusion.

According to the extrusion die for a metallic material as recited in the aforementioned Item [14], the inclination angle of the axis of the porthole is set to a predetermined angle, the metallic material can be supplied from the porthole to the extrusion hole in a stable manner.

According to the extrusion die for a metallic material as recited in the aforementioned Item [15], an aluminum or aluminum alloy extruded article can be produced.

According to the extrusion die for a metallic material as recited in the aforementioned Item [16], a tubular member having a circular cross-sectional configuration can be assuredly produced.

According to the extrusion die for a metallic material as recited in the aforementioned Item [17], a multi-bored hollow member having a plurality of passages arranged in the width direction thereof can be assuredly produced.

According to the invention as recited in the aforementioned Item [18], an extruded article production method having the same effects as mentioned above can be provided.

According to the invention as recited in the aforementioned Item [19], an extruded tubular member production method having the same effects as mentioned above can be provided.

According to the invention as recited in the aforementioned Item [20], a multi-bored hollow member production method having the same effects as mentioned above can be provided.

According to the invention as recited in the aforementioned Item [21] to [22], a die case for an extrusion die having the same effects as mentioned above can be provided.

Especially, according to the die case of the extrusion die as recited in the aforementioned Item [22], in the same reasons as in the aforementioned Item [9], the pressing force of the metallic material against the pressure receiving surface can be more assuredly dispersed in a balanced manner, resulting in more assuredly improved strength against the metallic material pressing force.

According to the invention as recited in the aforementioned Item [23], a metallic material extrusion method having the same effects as mentioned above can be provided.

According to the invention as recited in the aforementioned Item [24], a metallic material extruder having the same effects as mentioned above can be provided.

The above and/or other aspects, features and/or advantages of various embodiments will be further appreciated in view of the following description in conjunction with the accompanying figures. Various embodiments can include and/or exclude different aspects, features and/or advantages where applicable. In addition, various embodiments can combine one or more aspect or feature of other embodiments where applicable. The descriptions of aspects, features and/or advantages of particular embodiments should not be construed as limiting other embodiments or the claims.

BRIEF DESCRIPTION OF DRAWINGS

The preferred embodiments of the present invention are shown by way of example, and not limitation, in the accompanying figures, in which:

FIG. 1 is a perspective view of an extrusion die according to a first embodiment of the present invention;

FIG. 2 is a perspective cutout view of the extrusion die according to the first embodiment;

FIG. 3 is an exploded perspective view of the extrusion die according to the first embodiment;

FIG. 4 is a cross-sectional view of the extrusion die according to the first embodiment;

FIG. 5 is another cross-sectional view of the extrusion die according to the first embodiment;

FIG. 6 is an enlarged cutout perspective view showing the inside of the extrusion die according to the first embodiment;

FIG. 7 is a perspective cutout view showing a principal portion of an extruder to which the extrusion die of the first embodiment is applied;

FIG. 8 is a cross-sectional view showing the extrusion die of the first embodiment and its vicinity in an extruder;

FIG. 9 shows another cross-sectional view showing the extrusion die of the first embodiment and its vicinity in the extruder;

FIG. 10 is a perspective view showing a multi-bored hollow member extruded with an extruder according to the first embodiment;

FIG. 11 is an enlarged front cross-sectional view showing the multi-bored hollow member extruded with the extruder of the first embodiment;

FIG. 12 is a perspective view of an extrusion die according to a second embodiment of the present invention;

FIG. 13 is a perspective cutout view of the extrusion die according to the second embodiment;

FIG. 14 is an exploded perspective view of the extrusion die according to the second embodiment;

FIG. 15 is a perspective view of an extrusion die according to a first modified embodiment of the present invention;

FIG. 16 is a perspective view of an extrusion die according to a second modified embodiment of the present invention;

FIG. 17 is a perspective view of an extrusion die according to a third modified embodiment of the present invention;

FIG. 18A is an exploded perspective view showing a porthole die as a conventional extrusion die;

FIG. 18B is an exploded perspective view showing a spider die as a conventional extrusion die; and

FIG. 18C is a perspective view showing a bridge die as a conventional extrusion die.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following paragraphs, some preferred embodiments of the invention will be described by way of example and not limitation. It should be understood based on this disclosure that various other modifications can be made by those in the art based on these illustrated embodiments.

First Embodiment

FIGS. 1 to 5 show an extrusion die 10 according to a first embodiment of this invention. As shown in these drawings, this extrusion die 10 is designed to extrude a multi-bored hollow member 60 shown in FIGS. 10 and 11.

The hollow member 60 is a metal member which is an example of an aluminum or aluminum alloy heat exchanging tube 60 in this embodiment.

This hollow member 60 is a member to be employed in a heat exchanger, such as, e.g., a condenser for car air-conditioners, and has a flattened configuration. The hollow portion 61 of this hollow member 60 is extended in the tube length direction and divided into a plurality of heat exchanging passages 63 by a plurality of partitions 62 arranged in parallel with each other. These passages 63 are extended in the tube length direction and arranged in parallel with each other.

In the following explanation of this embodiment, a direction with which a tube length direction perpendicularly intersects and along which the passages 63 are arranged will be referred to as a “width direction,” and a direction with which a tube length direction perpendicularly intersects and with which the width direction perpendicularly intersects will be referred to as a “height direction (thickness direction).” Furthermore, in the following explanation of this embodiment, with reference to an extruded article formed by the die 10, the “upstream side” with respect to the extrusion direction of a metallic billet will be referred to as a “rear side”, and the “downstream side” thereof will be referred to as a “front side.”

As shown in FIGS. 1 to 5, the extrusion die 10 of this embodiment is equipped with a male die case 20, a female die case 25, a male die 30, a female die 40, and a flow control plate 50. In this embodiment, the die case is constituted by the male die case 20 and the female die case 25.

The male die case 20 is disposed at the upstream side (rear side) with respect to the female die case 25. This male die case 20 is formed independently with respect to the female die case 25 (i.e., separated from the female die case 25). As will be explained later, both the die cases 20 and 25 are coupled with each other.

The male die case 20 is formed into an approximately dome-shaped configuration having a pressure receiving portion 21 to which a billet is to be pressed and a circular press-fitting connecting portion 21 a integrally formed at the front surface side (i.e., front surface side periphery) of the pressure receiving portion 21. Furthermore, in the male die case 20, the external peripheral surface (rear surface) of the pressure receiving portion 21 constitutes a billet pressure receiving surface 22 as a metallic material pressure receiving surface.

The billet pressure receiving surface 22 of the male die case 20 is formed into a convex configuration protruded in a direction opposite to the extrusion direction (i.e., in the rear direction). This pressure receiving surface 22 is formed into a hemispherical convex configuration (configurations other than the spherical convex configuration will be referred in the following modified embodiments).

In the peripheral center of the pressure receiving portion 21 of the male die case 20, a male die holding slit 23 communicated with the internal hollow portion (welding chamber 12) is formed along the axial center A1 of the male die case 20. This male die holding slit 23 is formed into a flat rectangular cross-sectional configuration corresponding to the cross-sectional configuration of the male die 30. Furthermore, as best shown in FIG. 5, at both side portions of the rear end side of the male die holding slit 23, engaging stepped portions 23 a and 23 a for engaging the male die 30, which will be mentioned later, is formed.

In the external periphery of the pressure receiving portion 21 of the male die case 20, in detail, at both sides of the peripheral wall of the pressure receiving portion 21 across the axial center A1, a pair of portholes 24 and 24 are formed. Each porthole 24 has an elongated cross-sectional shape extending along the peripheral direction of the pressure receiving portion 21 and arranged at regular intervals in the peripheral direction. Furthermore, as best shown in FIG. 4, each porthole 24 is formed such that the axial center A2 of the porthole 24 approaches the axial center A1 of the pressure receiving portion 21 as it advances toward the downstream side (front side) and intersects with the axial center A1 of the pressure receiving portion 21 in an inclined state. The detail structure, such as, e.g., the inclination angle θ of this porthole 24, will be detailed later.

As shown in FIG. 2, at the front external peripheral portion of the press-fitting connecting portion 21 a of the male die case 20, two connecting rod mounting holes 22 a and 22 a are formed.

On the other hand, the female die case 25 is formed independently with respect to the male die case 20 and has a diameter larger than the diameter of the male die case 20.

At the rear end side external periphery of the female die case 25, in other words, at the external surface to be fitted by the male die case 20 (i.e., at the rear surface of the female die case 25), a press-fitting dented portion 25 a into which the press-fitting connecting portion 21 a of the male die case 20 can be forcibly fitted is provided. This press-fitting dented portion 25 a has an internal diameter smaller than the external diameter of the press-fitting connecting portion 21 a and a depth corresponding to the protruded length of the press-fitting connecting portion 21 a. The difference between the diameter of the press-fitting dented portion 25 a and that of the press-fitting connecting portion 21 a, etc., will be explained later.

In the bottom peripheral surface of the press-fitting dented portion 25 a, two connecting rod mounting holes 27 a and 27 a corresponding to the connecting rod mounting holes 22 a and 22 a of the male die case 20 are formed.

In the central portion of the press-fitting dented portion 25 a of the female die case 25, a female die holding dented portion 26 is formed. Formed in the bottom wall center of the holding dented portion 26 is a communication hole 26 b.

As shown in FIG. 3, on the inner peripheral surface of the female die holding dented portion 26, two key grooves 27 and 27 are formed so as to extend in the axial direction.

In the male die 30, the front end portion constitutes a mandrel 31. As shown in FIGS. 4 to 6, the front end portion of the mandrel 31 is configured to form hollow portion 61 and has a plurality of passage forming protruded portions 33 each corresponding to each passage 63 of the hollow member 60. These plural passage forming protruded portions 33 are arranged in line along the widthwise direction of the mandrel 31 at certain intervals. Each gap formed between adjacent passage forming protruded portions 33 constitutes a partition forming groove 32 for forming the partition 62 of the hollow member 60.

At the widthwise side edges of the rear end portion of the male die 30, engaging protrusions 33 a and 33 a corresponding to the aforementioned engaging stepped portions 23 a and 23 a of the male die holding slit 23 formed in the male die case 20 are integrally provided so as to protrude sideways.

This male die 30 is inserted into the male die holding slit 23 of the aforementioned male die case 20 from the side of the billet pressure receiving surface 22 and fixed therein. In this state, the engaging protrusions 33 a and 33 a of the male die 30 are engaged with the engaging stepped portions 23 a and 23 a in the male die holding slit 23 to be positioned. Thus, the mandrel 31 of the male die 30 is held in a state in which the mandrel 31 of the male die 30 is forwardly protruded from the male die holding slit 23 by a predetermined amount.

The basal end face (rear end face) of the male die 30 is formed so as to constitute a part of the spherical surface forming the billet pressure receiving surface 22 of the male die case 20, so that the basal end face (rear end face) of the male die 30 and the billet pressure receiving surface 22 form a prescribed smooth convex spherical surface.

As shown in FIG. 3, the female die 40 is cylindrical in configuration, and has, at its both sides of the peripheral surface, key protrusions 47 and 47 parallel to the central axis and corresponding to the keyways 27 and 27 of the female die holding hole 26 in the female die case 25.

The female die 40 is provided with a die hole (bearing hole 41) opened to the rear end face side and formed corresponding to the mandrel 31 of the male die 30 and a relief hole 42 communicated with the die hole 41 and opened to the front end face side.

The die hole 41 is provided with an inwardly protruded portion along the inner peripheral edge portion so that the outer peripheral portion of the hollow member 60 can be defined. The relief hole 42 is formed into a tapered shape gradually increasing the thickness (height) toward the front end side (downstream side) and opened at the downstream side.

The female die 40 is accommodated in the female die holding dented portion 26 of the female die case 25. In this accommodated state, the lower opening portion of the relief hole 42 of the female die 40 is disposed so that the lower opening portion is fitted in conformity with the communication hole 26 b formed in the bottom surface of the die holding dented portion 26, so that the relief hole 42 of the female die 40 is communicated with the lower side (downstream side) of the female die case 25.

The key protrusions 47 and 47 of the female die 40 are inserted into the keyways 27 and 27 of the female die case 25 and engaged therewith to be positioned with respect to the circumference direction about the central axis of the female die 40.

The flow control plate 50 is formed into a round shape in external periphery corresponding to the cross-sectional shape of the female die holding dented portion 26 of the female die case 25. Corresponding to the die hole (bearing hole) 41 of the female die 40, a central through-hole 51 is formed in the center of the flow control plate 50.

As shown in FIG. 3, the flow control plate 50 has, at its both sides of the external peripheral edge portion, key protrusions 57 and 57 corresponding to the keyways 27 and 27 of the female die 40 are formed.

The flow control plate 50 is disposed on the female die 40 with the flow control plate 50 accommodated in the female die holding dented portion 26. In this accommodate state, the key protrusions 57 and 57 of the flow control plate 50 are engaged with the keyways 27 and 27 of the female die case 25 to be positioned with respect to the circumference direction about the central axis of the flow control plate 50.

The male die case 20 mounting the male die 30 will be assembled to the female die case 25 mounting the female die 40 and the flow control plate 50 as follows.

In a state in which one half of the connecting rod 15 is inserted in the connecting rod mounting hole 27 a of the female die case 25 with the other half of the connecting rod 15 protruded outwardly, the press-fitting connecting portion 21 a of the male die case 20 is forcibly fitted in and fixed to the press-fitting dented portion 25 a of the female die case 25.

Thus, both the die cases 20 and 25 are connected each other with each other's axis aligned so that the male die case 20 is restrained from its periphery by the female die case 25.

This connection causes the positioning of the mandrel 31 of the male die 30 and the die hole (bearing hole) 41 of the female die 40 in the central through-hole 51 of the flow control plate 50. Furthermore, as shown in FIGS. 4 to 6, the mandrel 31 of the male die 30 is disposed within the die hole 41 of the female die 40, which forms a flat circular extrusion hole 11 between the mandrel 31 and the die hole 41. This extrusion hole 11 is formed into a cross-sectional configuration of the hollow member 60 to be formed by the widthwisely arranged plural partition forming grooves 32 of the mandrel 31.

In this embodiment, as mentioned above, the external diameter of the press-fitting connecting portion 21 a is formed to be slightly lager than the internal diameter of the press-fitting dented portion 25 a. In this embodiment, it is preferable that the diameter direction compression rate (press-fitting margin) of the press-fitting connecting portion 21 a with respect to the press-fitting dented portion 25 a falls within the following specific range.

In this embodiment, the press-fitting margin P is represented by the rate (percentage) of the diameter difference (L1-L2) between the external diameter L1 and the internal diameter L2 with respect to the internal diameter L2 where L1 is the external diameter of the press-fitting connecting portion 21 a and L2 is the internal diameter of the press-fitting dented portion 25 a. Concretely, the press-fitting margin P can be obtained by the following expression (1):

P=(L1−L2)×100/L2  (1)

In this embodiment, it is preferable that the aforementioned press-fitting margin P is set to 1 to 8%, more preferably 3 to 6%. In cases where the press-fitting margin P is set within the aforementioned specific range, the male die case 20 is restrained by the female die case 25 with appropriate compression force, improving the strength of the male die case 20, i.e., the strength of the billet pressure receiving portion 21, which in turn can improve the resistance to cracking and the durability. In other words, if the press-fitting margin P is too small, the male die case 20 cannot be sufficiently restrained by the female die case 25, causing deteriorated strength of the male die case 20, which in turn may result in deteriorated durability. To the contrary, if the press-fitting margin P is too large, the restraining force of the male die case 20 by the female die case 25 becomes too strong to deteriorate the strength of the male die case 20, which in turn may cause deteriorated durability.

In this invention, however, it is not always required that the press-fitting margin P is even along the entire periphery. For example, considering the deflections of the die cases 20 and 25 generated at the time of the extrusion molding, the press-fitting margin P can be changed within the aforementioned specific range.

It should be noted that in this disclosure “press-fitting” includes shrink fitting, such as, e.g., thermal insert or cooling fit, and shrink fitting can be employed in this invention.

In this embodiment, the outlet side end portions (front end portions) of the pair of portholes 24 and 24 are disposed so as to face the extrusion hole 11.

As previously mentioned, the axial center A2 of each porthole 24 is set to be inclined with respect to the axial center A1 of the male die case 20. As shown in FIG. 4, in this embodiment, it is preferable that the inclination angle θ of the axial center A2 of the porthole 24 with respect to the axial center A1 of the male die case 20 is set to 3 to 35°, more preferably 5 to 30°, still more preferably 5 to 25°. When the inclination angle θ is set so as to fall within the above specified range, the metallic material flows through the portholes 24 and 24 and the welding chamber 12 formed in both the die cases 20 and 25 in a stable manner, and then smoothly passes through around the entire periphery of the extrusion hole 11 in a balanced manner. As a result, a high quality extrusion molded article (extruded article) excellent in dimensional accuracy can be formed. In other words, if the inclination angle θ is too small, the metallic material passed through the portholes 24 and 24 and the welding chamber 12 cannot be smoothly introduced into the extrusion hole 11, which may sometimes make it difficult to stably obtain a high quality extrusion molded article. To the contrary, if the inclination angle θ is too large, the material flowing direction of the porthole 24 inclines largely, which increases the metallic material extrusion load, and therefore it is not preferable.

In this embodiment, it is preferable that the billet pressure receiving surface 22 of the male die case 20 has a configuration constituted by a convex spherical surface of a ⅙ sphere to a 4/6 sphere. When the billet pressure receiving surface 22 is formed into the aforementioned specific convex spherical configuration, the pressing force of a metal billet can be received by the billet pressure receiving surface 22 in a dispersed manner, resulting in sufficient strength, which in turn can extend the die life. That is, when a billet is pressed against the pressure receiving surface 22 having the specific convex spherical configuration, compressing force toward the center of the pressure receiving portion 21 is more assuredly applied to each portion of the pressure receiving surface 22. As a result, the shearing force generated at the position of the die case 20 exposed to the hollow portion of the die case 20, which is a portion where a largest shearing force will be generated, can be reduced assuredly. Thus, the strength of the die 10 against the pressing force of the billet can be improved more assuredly. In addition to the above, it also makes it possible to simplify the die configuration, reduce the size and weight, and also attain the cost reduction. In other words, if the billet pressure receiving surface 22 is formed into a configuration constituted by a convex spherical surface of a sphere smaller than a ⅙ sphere, such as, e.g., a convex spherical surface constituted by a ⅛ sphere, sufficient strength against the billet pressing force cannot be obtained, which may cause deteriorated die life due to generation of cracks. To the contrary, if the billet pressure receiving surface 22 is formed into a configuration constituted by a convex spherical surface of a sphere exceeding a 4/6 sphere, such as, e.g., a convex spherical surface configuration of a ⅚ sphere, the cost may be increased due to the complicated configuration.

In this embodiment, the sphere with a ratio, such as, e.g., a ⅛ sphere, a ⅙ sphere, or a 4/6 sphere, is defined by a partial sphere obtained by cutting a perfect sphere with a plane perpendicular to the central axis of the perfect sphere. That is, in this embodiment, an “n/m sphere (“m” and “n” are natural numbers, and n<m)” is defined by a partial sphere obtained by cutting a perfect sphere with a plane perpendicular to the central axis of the perfect sphere at a position where a distance from a surface of the perfect sphere to an inner position of the perfect sphere on the central axis (diameter) is n/m where the length of the central axis (diameter) of the perfect sphere is “1.”

As shown in FIG. 4, in this embodiment, the inner side surface 24 a and the outer side surface 24 b among the inner periphery of the porthole 24 are arranged approximately in parallel with each other and also approximately in parallel to the central axis A2 of the porthole 24. Furthermore, the inner side surface 24 a and the outer side surface 24 b of the porthole inner periphery are constituted as an inclined surface (tapered surface) inclined to the central axis A1 of the male die case 20, respectively.

The extrusion die 10 having the aforementioned structure is set in an extruder as shown in FIGS. 7 to 9. That is, the extrusion die 10 of this embodiment is set to a container 6 with the extrusion die 10 fixed in the die installation hole 5 a formed in the center of a plate 5. The extrusion die 10 is fixed by the plate 5 in a direction perpendicular to the extrusion direction and also fixed by a backer (not illustrated) in the extrusion direction.

A metal billet (metallic material), such as, e.g., an aluminum billet, inserted in the container 6 is pressed in the right direction (extrusion direction) in FIG. 7 via a dummy block 7. Thereby, the metal billet is pressed against the billet pressure receiving surface 22 of the male die case 20 constituting the extrusion die 10 to be plastically deformed. As a result, the metallic material passes through the pair of portholes 24 and 24 while being plastically deformed and then reaches the welding chamber 12 of both the die cases 20 and 25. Then, the material is forwardly extruded through the extrusion hole 11 into a cross-sectional configuration corresponding to the opening configuration of the extrusion hole 11. Thus, a metal extruded article (hollow member 60) is manufactured.

According to the extrusion die 10 of this embodiment, since the billet pressure receiving surface 22 is formed into a convex spherical configuration, when the metal billet is pressed against the billet pressure receiving surface 22, the pressing force can be received by the convex spherical surface in a dispersed manner. Therefore, the pressing force to be applied to each portion of the billet pressure receiving surface 22 in the direction of a normal line can be reduced, thereby increasing the strength against the pressing force of the metallic material, which results in sufficient durability.

In this embodiment, the portholes 24 for introducing material are formed in the external periphery of the pressure receiving portion 21 and the front end wall portion of the pressure receiving portion 21 is formed integrally and continuously in the peripheral direction. The existence of this continued peripheral wall portion can increase the strength of the male die case 20, which in turn can further increase the strength of the entire extrusion die.

Furthermore, since the male die case 20 is restrained from the periphery thereof by the female die case 25, the strength of the male die case 20 can be increased, which in turn can further increase the strength of the entire extrusion die. Thus, there is no portion weak in strength, such as a conventional bridge portion, and therefore it is not required to increase the size, such as, e.g., the thickness, beyond the necessity for the purpose of increasing the strength, which makes it possible to attain the reduced size and weight as well as the cost reduction.

Furthermore, in this embodiment, the portholes 24 and 24 are formed at positions away from the central axis A1 of the male die case 20, i.e., at the periphery of the pressure receiving portion 21, and the central axis A2 of each porthole 24 is inclined with respect to the central axis A1 of both the die cases 20 and 25 so as to gradually approach the central axis A1 of the male die case 20 toward the downstream side. Therefore, the metallic material passing through the portholes 24 and 24 can be stably extruded while being smoothly introduced to the axial center A1, i.e., the extrusion hole 11. Furthermore, in this embodiment, since the downstream side end portions (outlets) of the portholes 24 and 24 are faced toward the extrusion hole 11, the metallic material can be more smoothly introduced to the extrusion hole 11.

Furthermore, in this embodiment, since the portholes 24 and 24 are arranged at both sides of the height direction (thickness direction) of the flat extrusion hole 11, the metallic material can be more smoothly introduced into the extrusion hole 11 in a stable manner. Accordingly, the metallic material is extruded while evenly passing through the entire area of the extrusion hole 11 in a well-balanced manner, to thereby obtain a high quality extruded hollow member 60.

Especially like in this embodiment, even in the case of obtaining a hollow member 60 having a complicated configuration, such as, e.g., a flat harmonica tube configuration, metallic material can be introduced into the entire region of the extrusion hole 11 in a well-balanced manner, which can further improve the quality.

For reference, in cases where an aluminum heat exchanging tube (hollow member) provided with a plurality of passages 63 each rectangular in cross-section having a height of 0.5 mm and a width of 0.5 mm, in a conventional extrusion die, since the strength was not sufficient, cracks generated in the male die caused a shortened die life. On the other hand, in the extrusion die 10 according to the present invention, since the strength is sufficient, no crack will be generated in the die. Therefore, the wear of the die becomes a factor of the die life, which can remarkably improve the die life.

For example, according to the results of experiments relevant to a die life performed by the present inventors, in the extrusion die according to the present invention, the length of die life was extended about three times as compared with a conventional one.

Moreover, in the present invention, since it has sufficient pressure resistance (strength), the extrusion limit speed can be raised considerably. For example, in a conventional extrusion die, the upper limit of the extrusion speed was 60 m/min. On the other hand, in the extrusion die according to the present invention, the upper limit of the extrusion speed can be raised up to 150 m/min, i.e., the extrusion limit speed can be raised about 2.5 times, and therefore the productive efficiency can be further improved.

Second Embodiment

FIGS. 12 to 14 show an extrusion die 10 according to a second embodiment of the present invention. As shown in these figures, this extrusion die 10 of this second embodiment is greatly different from the extrusion die 10 of the first embodiment as follows. That it, in the first embodiment, the die 10 is configured to extrude a flat multi-bored tubular member. On the other hand, in the second embodiment, the die 10 is configured to extrude a tubular member circular in cross-section.

The extrusion die 10 of the second embodiment includes a die case consisting of a male die case 20 and a female die case 25, a male die 30 having a mandrel 31 circular in cross-section, a female die 40 having a die hole 41 circular in cross-section, and a flow control plate 50.

The die holding hole 23 of the male die case 20 is formed into a columnar configuration corresponding to the male die 30. A total of three portholes 24 are formed in the male die case 20 at equal circumferential intervals.

In the same manner as in the first embodiment, both the die cases 20 and 25 are fixedly coupled with each other using connecting rods 15 in a state in which the male die 30 is inserted the die holding hole 23 of the male die case 20 and the female die 40 and the flow control plate 50 are accommodated within the die holding dented portion 26 of the female die case 25.

In this coupled state, the mandrel 31 of the male die 30 is disposed inside the die hole 41 of the female die 40 to thereby form a circular extrusion hole 11 between the mandrel 31 and the die hole 41.

The other structure of the extrusion die 10 of this second embodiment is substantially the same as the structure of the extrusion die 10 of the first embodiment. Accordingly, the cumulative explanation will be omitted by allotting the same or corresponding reference numeral to the same or corresponding portion.

This extrusion die 10 of this second embodiment is set to an extruder as explained in the first embodiment shown in FIG. 7 to produce an extruded tubular member circular in cross-section.

In this second embodiment, in the same manner as in the first embodiment, the same functions and effects as those of the first embodiment can be attained.

Modified Embodiment

In each of the aforementioned embodiments, a male die case 20 having a semispherical pressure receiving portion 21 was exemplified. In this invention, however, it should be recognized that the configuration of the pressure receiving portion 21 of the male die case 20 is not specifically limited.

For example, the present invention can be applied to a male die case 20 having a partial spherical configuration, such as, e.g., a ⅙- 4/6 spherical configuration.

Furthermore, the configuration of the pressure receiving portion 21 of the male die case 20 is not limited to a spherical configuration, but can be, for example, a polyhedral configuration, such as, a sixteen-sided pyramid configuration, as shown in FIG. 15. In cases where the pressure receiving portion 21 is formed into a polyhedral configuration, the configuration can be, for example, a circumferentially arranged polyhedral configuration in which a plurality of side surfaces are arranged in the circumferential direction, such as, a pyramid configuration, an axially arranged polyhedral configuration in which a plurality of side surfaces are arranged in the axial direction, or a polyhedral configuration in which the circumferentially arranged polyhedral configuration and the axially arranged polyhedral configuration are combined. Furthermore, each side surface of the polyhedron is not limited to a flat surface, but can be a curved surface.

Furthermore, in the present invention, as shown in FIG. 16, the pressure receiving portion 21 of the male die case 20 can be formed to have a semi-elliptical configuration in side view obtained by dividing an elliptical configuration by a line perpendicular to the minor axis and an elliptical or oval configuration as seen from the axial direction of the male die case 20 (as seen from the upstream side of the extrusion direction).

Furthermore, in the present invention, as shown in FIG. 17, the pressure receiving portion 21 of the male die case 20 can be formed to have a semi-elliptical or semi-oval configuration in side view obtained by dividing an elliptical configuration by a line perpendicular to the major axis and having a protrusion dimension along the axial direction of the male die case 20 longer than the radius dimension along a direction perpendicular to the axial direction.

Furthermore, in the aforementioned embodiments, the die case is divided into two members, i.e., the male die and the female die. The present invention, however, is not limited to the above, and can allow a die case divided into three or more members.

In the aforementioned embodiments, the explanation was directed to the case in which two or three portholes 24 are formed. The present invention, however, is not limited to the above, and can allow a die case having four or more portholes.

Furthermore, in the aforementioned embodiments, the explanation was directed to the case in which only a single extrusion die is set in a container. The present invention, however, is not limited to the above. In the extruder according to the present invention, it can be configured such that two or more extrusion dies are set in a container.

In the aforementioned embodiments, the explanation was directed to the case in which a flat multi-bored tubular member or a round tubular member is extruded. However, it should be noted that in the present invention the configuration of the extruded article is not specifically limited.

Furthermore, in the aforementioned embodiments, the explanation was directed to the case in which the male die case 20 and the male die 30 are formed separately. The present invention, however, is not limited to the above, and can be applied to the case in which the male die 30 is integrally formed to the male die case 20. Furthermore, in the present invention, the female die 40 and the female die case 25 can be integrally formed, or the flow control plate 50 and the female die case 25 can be integrally formed, or the flow control plate 50 and the female die 40 are integrally formed. In the case of integrally forming a die or case as mentioned above, the processing cost can be reduced.

Furthermore, in the present invention, as shown in the aforementioned embodiments, it is preferable that the rear end face (basal end face) of the male die 30 is formed as a part of the convex surface (spherical surface) corresponding to the billet pressure receiving surface 22 of the pressure receiving portion 21 and that the rear end face of the male die 30 and the billet receiving surface 22 constitute a desired smooth convex surface (spherical surface). In the present invention, however, the configuration of the rear end face (basal end face) of the male die 30 is not limited to the above, and can be, for example, formed into the following configuration. That is, in the present invention, in cases where the surface area of the rear end face of the male die 30 is, for example, ⅓ or less of the surface area of the billet pressure receiving surface 22 of the die 10, the rear end face of the male die 30 can be constituted by a part of a columnar external peripheral surface in which the rear end face is circular corresponding to the billet pressure receiving surface 22 in the width direction (longitudinal direction) and straight in the thickness direction (direction perpendicular to the longitudinal direction) because of the following reasons. That is, in cases where the surface area of the rear end face of the male die 30 is small as mentioned above, influence on die life and extrusion load due to the fact that the rear end face of the male die 30 is formed not into a part of a convex surface (spherical surface) but into a part of an external periphery of a circular column is small and the processing cost of the rear end face of the male die 30 can be reduced.

In each extrusion die according to the aforementioned modified embodiments, the same functions and effects as those of the aforementioned embodiment can be attained.

EXAMPLE

TABLE 1 Press-fitting compression rate (Press-fitting margin) Die life Life limiting factor Example 1 0.5% 2.0 ton Generation of cracks in male die Example 2 1.0% 3.5 ton Wear of male die, Minute cracks Example 3 3.0% 4.0 ton Wear of male die Example 4 6.0% 4.0 ton Wear of male die Example 5 8.0% 3.5 ton Wear of male die, minute cracks in male die case Example 6 9.0% 3.0 ton Generation of cracks in male die case Comparative — 0.7 ton Generation of cracks Example 1 in male die

Example 1

As shown in Table 1, an extrusion die 10 for forming a flat multi-bored tubular member, which was the same as in the first embodiment shown in FIGS. 1 to 6, was prepared. In the male die case 20 of this extrusion die 10, the pressure receiving portion 21 was formed into a ½ spherical configuration (semispherical configuration) having a radius of 30 mm.

The male die case 20 had a pair of portholes 24 and 24 and the inclination angle θ of the axis A2 of each porthole 24 with respect to the axis A1 of the male die case 20 was adjusted to 100.

The press-fitting margin P between the press-fitting connecting portion 21 a of the male die case 20 and the press-fitting dented portion 25 a of the female die case 25 was adjusted to 0.5%.

The male die 30 was adjusted to 2.0 mm in height of mandrel 31, 19.2 mm in width of mandrel 31, 1.2 mm in height of passage forming protruded portion 33, 0.6 mm in width of passage forming protruded portion 33, and 0.2 mm in width of partition forming groove 32.

The female die 40 was adjusted to 1.7 mm in height of die hole 41 and 20.0 mm in width of die hole 41.

As shown in FIGS. 7 to 9, the extrusion die 10 was set to an extruder similar to the extruder shown in the embodiment and extrusion was performed to produce a flat multi-bored tubular member (heat exchanging tubular member) as shown in FIGS. 10 and 11.

The die life (the amount (tons) of introduced material until cracks or wear occurs) was measured, and the die life limiting factors were investigated. The result and the press-fitting margin are also shown in Table 1.

Example 2

An extrusion die 10 the same as in Example 1 was prepared except that the press-fitting margin P was set to 1.0% as shown in Table 1.

After performing an extrusion in the same manner as in Example 1, the same evaluation was performed.

Example 3

An extrusion die 10 the same as in Example 1 was prepared except that the press-fitting margin P was set to 3.0% as shown in Table 1.

After performing an extrusion in the same manner as in Example 1, the same evaluation was performed.

Example 4

An extrusion die 10 the same as in Example 1 was prepared except that the press-fitting margin P was set to 6.0% as shown in Table 1.

After performing an extrusion in the same manner as in Example 1, the same evaluation was performed.

Example 5

An extrusion die 10 the same as in Example 1 was prepared except that the press-fitting margin P was set to 8.0% as shown in Table 1.

After performing an extrusion in the same manner as in Example 1, the same evaluation was performed.

Example 6

An extrusion die 10 the same as in Example 1 was prepared except that the press-fitting margin P was set to 9.0% as shown in Table 1.

After performing an extrusion in the same manner as in Example 1, the same evaluation was performed.

Comparative Example 1

A bridge type extrusion die was prepared. In this die the diameter was 60 mm, the height (length along the extrusion direction) was 30 mm, the occupation area was the same as that of the extrusion die of each example, and the billet pressure receiving surface was formed into a flat surface perpendicular to the extrusion direction. The inclination angle θ of the metallic material introducing direction with respect to the axial center of the die was substantially 0°. The other structure was the same as that of the aforementioned Example.

This extrusion die was set to an extruder in the same manner as mentioned above and extruded an extruded article. Then, the same evaluation was performed.

Evaluation of Examples 1-6 and Comparative Example 1

As shown in Table 1, in Comparative Example 1, cracks in the male die became die life limiting factors and the die life was short. In Example 1, although cracks in the male die were die life limiting factors, the die life was at least longer than that of Comparative Example 1. In Example 2, although minute cracks were generated in the male die, the wear of the male die became main die life limiting factors, and therefore the die life was longer than that of Example 1. In Examples 3 and 4, the male die wear was the main die life limiting factor and the die life was sufficiently long. In Example 5, although minute cracks were generated in the case, the main die life limiting factor was the male die wear and a certain die life was kept. In Example 6, although cracks in the male die case were the main die limiting factor, the die life was at least longer than that of Comparative Example 1.

The further consideration of the aforementioned evaluation revealed that the die having the press-fitting margin of 1 to 8% (Example 2-5) could secure sufficient strength and therefore the porthole could be enlarged in the same stress value of the die case with respect to the pressing force of the metallic material. Accordingly, in Example 2-5, the extrusion resistance was small, resulting in reduced processing heat generation, which in turn could extend the die life. Especially, in the die in which the press-fitting margin was 3 to 6% (Example 3, 4), the die rigidity improving effects could be remarkably enhanced, resulting an increased porthole size, which in turn could extend the die life dramatically.

In the die in which the press-fitting margin was relatively small (Example 1), the restraint of the male die case by the female die case was somewhat insufficient and the die strength was slightly decreased. Thus, the wear die life was slightly shortened with respect to preferable examples (Examples 2-5).

In the die in which the press-fitting margin was relatively large (Example 6), the restrain force of the male die case by the female die case was excessive, resulting in slightly deteriorated die strength. Thus, as compared with the die having an appropriate restrain force (Examples 2 to 5), the wear die life was slightly shortened.

TABLE 2 Porthole Extrusion inclination Die life limiting load angle Die life factor (×10⁴N) Example 7 1.5° 10 ton Generation of male 1,400 die cracks Example 8 3.0° 12 ton Male die wear, 1,450 minute cracks Example 9 6.0° 12 ton Male die wear 1,500 Example 10 15.0° 12 ton Male die wear 1,650 Example 11 30.0° 12 ton Male die wear 1,700 Example 12 35.0° 12 ton Male die wear, 1,750 minute cracks Example 13 38.0°  9 ton Generation of male 1,850 die cracks Comparative —  7 ton Generation of male 1,600 Example 2 die cracks

Example 7

As shown in Table 2, an extrusion die 10 for forming a tubular member round in cross-section, which was the same as in the second embodiment shown in FIGS. 12 to 14, was prepared. In the male die case 20 of this extrusion die 10, the pressure receiving potion 21 was formed into a ½ spherical configuration (semispherical configuration) having a radius of 50 mm.

The male die case 20 had three portholes 24, 24 and 24 arranged at equal circumferential intervals, and the inclination angle θ of the axis A2 of each porthole 24 with respect to the axis A1 of the male die case 20 was adjusted to 15°.

The mandrel 31 of the male die 30 was round in cross-section and 30 mm in diameter. The die hole 41 of the female die 40 was round in cross-section and 32 mm in diameter.

This extrusion die 10 was set in the extruder similar to the extruder of the aforementioned embodiment shown in FIGS. 7 to 9, and a tubular member round in cross-section was produced by performing extrusion. The extrusion load at the time of the extrusion was 1,400×10⁴ N.

The extrusion load N and the die life were measured.

Furthermore, the die life limiting factors were investigated. The result and the porthole inclination angle θ are also shown in Table 2.

Example 8

As shown in Table 1, an extrusion die 10 similar to the above extrusion die except that the porthole inclination angle θ was adjusted to 3.0° was prepared.

An extrusion was performed in the same manner as mentioned above and the same evaluation was performed. The extrusion load at the time of the extrusion was 1,450×10⁴ N.

Example 9

As shown in Table 1, an extrusion die 10 similar to the above extrusion die except that the porthole inclination angle θ was adjusted to 6.0° was prepared.

An extrusion was performed in the same manner as mentioned above and the same evaluation was performed. The extrusion load at the time of the extrusion was 1,500×10⁴ N.

Example 10

As shown in Table 1, an extrusion die 10 similar to the above extrusion die except that the porthole inclination angle θ was adjusted to 15.0° was prepared.

An extrusion was performed in the same manner as mentioned above and the same evaluation was performed. The extrusion load at the time of the extrusion was 1,650×10 N.

Example 11

As shown in Table 1, an extrusion die 10 similar to the above extrusion die except that the porthole inclination angle θ was adjusted to 30.0° was prepared.

An extrusion was performed in the same manner as mentioned above and the same evaluation was performed. The extrusion load at the time of the extrusion was 1,700×10⁴ N.

Example 12

As shown in Table 1, an extrusion die 10 similar to the above extrusion die except that the porthole inclination angle θ was adjusted to 35.0° was prepared.

An extrusion was performed in the same manner as mentioned above and the same evaluation was performed. The extrusion load at the time of the extrusion was 1,750×10⁴ N.

Example 13

As shown in Table 1, an extrusion die 10 similar to the above extrusion die except that the porthole inclination angle θ was adjusted to 38.0° was prepared.

An extrusion was performed in the same manner as mentioned above and the same evaluation was performed. The extrusion load at the time of the extrusion was 1,850×10⁴ N.

Comparative Example 2

A bridge type extrusion die was prepared. In this die, the diameter was 100 mm, the height (length along the extrusion direction) was 80 mm, the occupation area was the same as that of the extrusion die of each example, and the billet pressure receiving surface was formed into a flat surface perpendicular to the extrusion direction. The inclination angle θ of the metallic material introducing direction with respect to the axial center of the die was substantially 0°. The other structure was the same as that of the aforementioned Examples 7 to 13.

This extrusion die was set to an extruder in the same manner as mentioned above and extruded an extruded article. Then, the same evaluation was performed. The extrusion load at the time of the extrusion was 1,600×10⁴ N.

Evaluation of Examples 7 to 13 and Comparative Example 2

As shown in Table 2, in Comparative Example 2, cracks in the male die became a die life limiting factor and the die life was short. In Example 7 and Example 13, although cracks in the male die were a die life limiting factor, the die life was at least longer than that of Comparative Example 2. In Example 8 and Example 12, although minute cracks were generated in the male die, the wear of the male die became the main die life limiting factor, and therefore the die life was sufficiently long. In Examples 9 to 11, the male die wearing was the main die life limiting factor, and the die life was sufficiently long.

In summary, in Examples 7-13, as compared with Comparative Example 2, the die life was long. Among Examples 7 to 13, the dies each having a porthole inclination angle of 3.0 to 35.00 (Example 8 to 12) were long in die life.

Among Examples, as the porthole inclination angle θ becomes smaller, the extrusion load decreases. Therefore, it is considered to be preferable that the porthole inclination angle θ is small except for the case in which an extruded article complicated in configuration, such as, e.g., a flat multi-bored tube, is extruded.

TABLE 3 Spherical size of billet pressure Die life receiving surface (ton/die) Example 14 ⅛ 1.2 Example 15 ⅙ 2.0 Example 16 ⅓ 2.5 Example 17 ½ 3.0 Example 18 4/6 3.0 Example 19 ⅚ 3.0

Example 14

As shown in Table 3, according to the aforementioned embodiment, a male die case 20 having a billet pressure receiving surface 22 constituted by an external surface (convex surface) of a ⅛ sphere with a spherical radius of 45.4 mm was prepared. The diameter of this pressure receiving surface portion 21 was adjusted to 60 mm.

The male die case 20 had a pair of portholes 24 and 24 and the inclination angle θ of the axis A2 of each porthole 24 with respect to the axis A1 of the male die case 20 was adjusted to 25°.

The male die 30 was adjusted to 2.0 mm in height of mandrel 31, 19.2 mm in width of mandrel 31, 1.2 mm in height of passage forming protruded portion 33, 0.6 mm in width of passage forming protruded portion 33, and 0.2 mm in width of partition forming groove 32. Furthermore, the female die 40 was adjusted to 1.7 mm in height of die hole 41 and 20.0 mm in width of die hole 41.

The press-fitting margin P between the press-fitting connecting portion 21 a of the male die case 20 and the press-fitting dented portion 25 a of the female die case 25 was adjusted to 1.0%.

As shown in FIGS. 7 to 9, the extrusion die 10 was set to an extruder similar to the extruder shown in the aforementioned embodiment, and extrusion was performed to produce a tubular member (heat exchanging tubular member 60) having a cross-sectional configuration corresponding to the extrusion hole 11 between the male die 30 and the female die 40.

Then, the die life (ton/die) was measured. The result is shown in Table 3.

Example 15

As shown in Table 3, an extrusion die 10 similar to the extrusion die of Example 14 except that the billet pressure receiving surface 22 was constituted by a convex spherical surface of a ⅙ sphere and the spherical diameter was set to 40.3 mm was prepared and set to an extruder similar to the extruder as mentioned above. A hollow member was produced by performing extrusion in the same manner as mentioned above.

Example 16

As shown in Table 3, an extrusion die 10 similar to the extrusion die of Example 14 except that the billet pressure receiving surface 22 was constituted by a convex spherical surface of a ⅓ sphere and the spherical diameter was set to 32.0 mm was prepared and set to an extruder similar to the extruder as mentioned above. A hollow member was produced by performing extrusion in the same manner as mentioned above.

Example 17

As shown in Table 3, an extrusion die 10 similar to the extrusion die of Example 14 except that the billet pressure receiving surface 22 was constituted by a convex spherical surface of a ½ sphere and the spherical diameter was set to 30.0 mm was prepared and set to an extruder similar to the extruder as mentioned above. A hollow member was produced by performing extrusion in the same manner as mentioned above.

Example 18

As shown in Table 3, an extrusion die 10 similar to the extrusion die of Example 14 except that the billet pressure receiving surface 22 was constituted by a convex spherical surface of a 4/6 sphere and the spherical diameter was set to 32.0 mm was prepared and set to an extruder similar to the extruder as mentioned above. A hollow member was produced by performing extrusion in the same manner as mentioned above.

Example 19

As shown in Table 3, an extrusion die 10 similar to the extrusion die of Example 14 except that the billet pressure receiving surface 22 was constituted by a convex spherical surface of a ⅚ sphere and the spherical diameter was set to 40.3 mm was prepared and set to an extruder similar to the extruder as mentioned above. A hollow member was produced by performing extrusion in the same manner as mentioned above.

Evaluation of Examples 14 to 19

As shown in Table 3, in the die in which the spherical radius of the billet pressure receiving surface 22 was large and the protruded amount was relatively small (Example 14), the die life was slightly shortened.

In the die in which the spherical radius of the billet pressure receiving surface 22 was small and the protruded amount was relatively large (Example 19), although the die life could be kept long, it seems to be slightly difficult to perform the processing of the billet pressure receiving surface.

On the other hand, in the die in which the billet pressure receiving surface 22 was formed into an appropriate convex surface configuration, i.e., a convex spherical surface of a ⅙ to 4/6 sphere (Examples 15 to 18), the die life could be extended and the die production cost could be reduced. Among other things, in the die in which the billet pressure receiving surface 22 was formed into a spherical surface of a ½ sphere (Example 17), the die production cost could be kept low while keeping sufficiently long die life, which was an excellent result.

Comparing with the die according to Example 17, in the die in which the billet pressure receiving surface 22 was formed into a convex spherical surface of a 4/6 sphere (Example 18), the die production cost was increased, which was an inferior result among Examples 15 to 18.

INDUSTRIAL APPLICABILITY

The extrusion die for a metallic material according to the present invention can be used in manufacturing an extruded product such as a hollow tube including, e.g., a heat exchanging tube for use in an automobile air-conditioning gas cooler, evaporator, or household hot-water supplying device.

It should be understood that the terms and expressions used herein are used for explanation and have no intention to be used to construe in a limited manner, do not eliminate any equivalents of features shown and mentioned herein, and allow various modifications falling within the claimed scope of the present invention.

While the present invention may be embodied in many different forms, a number of illustrative embodiments are described herein with the understanding that the present disclosure is to be considered as providing examples of the principles of the invention and such examples are not intended to limit the invention to preferred embodiments described herein and/or illustrated herein.

While illustrative embodiments of the invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, but includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present disclosure, the term “preferably” is non-exclusive and means “preferably, but not limited to.” In this disclosure and during the prosecution of this application, means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; b) a corresponding function is expressly recited; and c) structure, material or acts that support that structure are not recited. In this disclosure and during the prosecution of this application, the terminology “present invention” or “invention” may be used as a reference to one or more aspect within the present disclosure. The language present invention or invention should not be improperly interpreted as an identification of criticality, should not be improperly interpreted as applying across all aspects or embodiments (i.e., it should be understood that the present invention has a number of aspects and embodiments), and should not be improperly interpreted as limiting the scope of the application or claims. In this disclosure and during the prosecution of this application, the terminology “embodiment” can be used to describe any aspect, feature, process or step, any combination thereof, and/or any portion thereof, etc. In some examples, various embodiments may include overlapping features. In this disclosure and during the prosecution of this case, the following abbreviated terminology may be employed: “e.g.” which means “for example;” and “NB” which means “note well.” 

1. An extrusion die for a metallic material, comprising: a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material; a female die case disposed at a front side of the male die case: a male die provided in the male die case; and a female die provided in the female die case to form an extrusion hole by and between the female die and the male die, wherein the metallic material pressure receiving surface of the pressure receiving portion is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is formed in an external periphery of the pressure receiving portion, wherein a press-fitting connecting portion is formed at a front side external periphery of the male die case, and a press-fitting dented portion is formed at a rear side external periphery of the female die case, and wherein the press-fitting connecting portion is press-fitted in the press-fitting dented portion, whereby both the die cases are connected with each other with the male die case restrained from periphery thereof by the female die case.
 2. The extrusion die for a metallic material as recited in claim 1, wherein an axis of the porthole is disposed so as to incline with respect to an axis of the male die case so that the axis of the porthole approaches the axis of the male die case toward a downstream side.
 3. The extrusion die for a metallic material as recited in claim 1 or 2, wherein a radius direction compression rate (press-fitting margin) of the press-fitting connecting portion with respect to the press-fitting dented portion is set to 1 to 8%.
 4. The extrusion die for a metallic material as recited in any one of claims 1 to 3, wherein the male die case and the male die are formed separately, and the male die is held by the male die case.
 5. The extrusion die for a metallic material as recited in any one of claims 1 to 3, wherein the male die is integrally formed to the male die case.
 6. The extrusion die for a metallic material as recited in any one of claims 1 to 5, wherein the female die is integrally formed to the female die case.
 7. The extrusion die for a metallic material as recited in any one of claims 1 to 6, wherein a flow control plate for controlling a metallic material flow is integrally formed to the male die case.
 8. The extrusion die for a metallic material as recited in any one of claims 1 to 7, wherein the pressure receiving portion is formed into a semi-spherical configuration.
 9. The extrusion die for a metallic material as recited in any one of claims 1 to 7, wherein the metallic material pressure receiving surface is constituted by a convex spherical surface of a ⅙ to 4/6 sphere.
 10. The extrusion die for a metallic material as recited in any one of claims 1 to 7, wherein the pressure receiving portion is formed into a polyhedral configuration in which a plurality of side surfaces are disposed on the pressure receiving surface.
 11. The extrusion die for a metallic material as recited in any one of claims 1 to 7, wherein the pressure receiving portion is formed to have an elliptical or oval configuration as seen from an axial direction of the male die case.
 12. The extrusion die for a metallic material as recited in any one of claims 1 to 7, wherein a protrusion dimension of the pressure receiving portion along an axial direction of the male die case is set to be longer than a radius dimension of the pressure receiving portion along a direction perpendicular to the axial direction, and wherein the pressure receiving portion is formed to have a semi-elliptical or semi-oval configuration as seen from a direction perpendicular to the axial direction.
 13. The extrusion die for a metallic material as recited in any one of claims 1 to 12, wherein the male die case has a plurality of the portholes arranged at equal intervals in a peripheral direction around an axis of the male die case.
 14. The extrusion die for a metallic material as recited in claim 2, wherein an inclination angle of the axis of the porthole is set to 3 to 35° with respect to the axis of the male die case.
 15. The extrusion die for a metallic material as recited in any one of claims 1 to 14, wherein the metallic material is aluminum or aluminum alloy.
 16. The extrusion die for a metallic material as recited in any one of claims 1 to 15, wherein a circular extrusion hole is formed by and between the male die and the female die so that the metallic material is extruded through the extrusion hole to form a tubular member circular in cross-section.
 17. The extrusion die for a metallic material as recited in any one of claims 1 to 15, wherein an extrusion hole having a flat circular cross-sectional configuration with a height (thickness) smaller than a width is formed by the male die and the female die, wherein a portion of the male die corresponding to the extrusion hole is formed into a comb-line configuration having a plurality of passage forming protrusions arranged in a width direction, and wherein the metallic material passes through the extrusion hole to form a multi-bored hollow extruded member having a plurality of passages arranged in a width direction.
 18. An extruded article production method for producing an extruded article by using the extrusion die as recited in any one of claims 1 to
 15. 19. An extruded tubular member production method for producing an extruded tubular member by using the extrusion die as recited in claim
 16. 20. A multi-bored hollow member production method for producing a multi-bored hollow member by using the extrusion die as recited in claim
 17. 21. A die case for en extrusion die, comprising: a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material, and a male die being provided in the male die case; and a female die case disposed at a front side of the male die case, a female die being provided in the female die case, wherein the metallic material pressure receiving surface of the pressure receiving portion is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is formed in an external periphery of the pressure receiving portion, wherein a press-fitting connecting portion is formed at a front side external periphery of the male die case, and a press-fitting dented portion is formed at a rear side external periphery of the female die case, and wherein the press-fitting connecting portion is press-fitted in the press-fitting dented portion, whereby both the die cases are connected with each other with the male die case restrained from periphery thereof by the female die case.
 22. The die case for an extrusion die as recited in claim 21, wherein the metallic material pressure receiving surface is constituted by a convex spherical surface of a ⅙ to 4/6 sphere.
 23. A metallic material extrusion method, comprising the steps of: preparing a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material, a female die case disposed at a front side of the male die case, a male die provided in the male die case, and a female die provided in the female die case to form an extrusion hole by and between the male die and the female die; forming a porthole for introducing a metallic material in an external periphery of the pressure receiving portion having a convex configuration constituting the metallic material pressure receiving surface protruded rearward; forming a press-fitting connecting portion at a front side external periphery of the male die case and forming a press-fitting dented portion at a rear side external periphery of the female die case; connecting both the die cases with the male die case restrained from its periphery thereof by the female die case by press-fitting the press-fitting connecting portion into the press-fitting dented portion; and introducing the metallic material pressed against the metallic material pressure receiving surface in both the die cases via the porthole with both the die cases connected to thereby pass through the extrusion hole.
 24. A metallic material extruder comprising a container and an extrusion die set in the container, the extruder being configured to supply a metallic material in the container to the extrusion die, wherein the extrusion die comprises: a male die case having a pressure receiving portion with an external surface constituting a metallic material pressure receiving surface, the male die case being disposed with the pressure receiving portion facing rearward against an extrusion direction of the metallic material; a female die case disposed at a front side of the male die case; a male die provided in the male die case; and a female die provided in the female die case to form an extrusion hole by and between the male die and the female die, wherein the metallic material pressure receiving surface of the pressure receiving portion is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is formed in an external periphery of the pressure receiving portion, wherein a press-fitting connecting portion is formed at a front side external periphery of the male die case and a press-fitting dented portion is formed at a rear side external periphery of the female die case, wherein both the die cases are connected with each other with the male die case restrained from its periphery thereof by the female die case by press-fitting the press-fitting connecting portion into the press-fitting dented portion, and wherein the metallic material pressed against the metallic material pressure receiving surface is introduced in both the die cases via the porthole to thereby pass through the extrusion hole. 